This 6 arm study will evaluate the efficacy and safety of different doses of P38 Inhibitor (4) in patients with RA currently having an inadequate clinical response to methotrexate. Patients will be randomized to receive P38 Inhibitor (4) (50,150 or 300 qd po,and 25 or 75 bid po) or placebo, and will remain on the stable dose of methotrexate. The anticipated time on study treatment is <3 months, and the target sample size is 100-500 individuals.